Nov. 1895.] BOTANICAL SOCIETY OF EDINBURGH. 465 



was attached to the granules described or figured. It is 

 to Brown that the credit is due of extending observations 

 of the nucleus to cells of many different parts of the same 

 plants, and to plants of various families, chiefly of Mono- 

 cotyledons, but also in some cases of Dicotyledons. It is 

 peculiarly interesting to us now that he observes its 

 occurrence in the cells of the ovule, and in the pollen- 

 mother-cells and tetrads. He thus approached at once the 

 focal point of interest, viz. the relation of the nucleus to 

 reproduction ; but the demonstration of the part which it 

 plays in this process did not come for nearly half a century 

 after he wrote. 



A noteworthy feature in the three pages of print into 

 which he compressed his account of the nucleus or areola, 

 is the caution displayed. It is a plain statement of facts 

 of observation. He does not generalise on insufficient 

 crrounds ; he does not even dwell on cases where the 

 nucleus has not been seen, but he states where it has been 

 seen. He does not state that it is a constant feature of 

 the cell, but his attitude is distinctly that of expectancy 

 that it will be found if properly sought for. His imme- 

 diate followers, however, were not so reticent, and the 

 varying size, position, and prominence of the nucleus, 

 together with its elusive behaviour in division, greatly 

 delayed further progress. These circumstances, doubtless, 

 explain the position of Meyer, which we may place in 

 antithesis to the truly scientific attitude of Brown. In his 

 "Bflanzen-Physiologie" (1837, vol. i. p. 209) he remarks: 

 " The occurrence of these nuclei within the cells does not 

 seem to be constant at all times in the plant, and where they 

 do occur, these structures are only to be recognised in a few 

 cells. In the majority of cells they are absent. Perhaps 

 the nucleus also is a sort of nourishment-reserve." And so 

 was initiated the idea of a coming and going, a breaking up 

 and reconstitution of the nucleus, while there naturally 

 followed the view that free nuclear formation is a matter of 

 common occurrence. This view largely dominated the 

 expressions of Schleiden and his follov^^ers. It was not till 

 forty years later that Strasburger (1879) summed up his 

 evidence on the continuity of existence of the nucleus in 

 the memorable sentence (Bot. Zeit., 1879, p. 278): "I 



